[HECnet] DECnet compatibility update

[Peter Coghlan]

I can successfully connect from a VAX (4000-700a) running VMS v7.3 to
the PDP-11/53 (again, running RSTS/E v10.1) via:

$ set host/appl=rterm 61.4

Terminal control is a bit wonky, but it works.   This is what crashes
from the Alpha running VMS v8.3.


I can also add that

$ set host/appl=rterm 61.4

crashes out in a similar way on an Alpha running V8.2. However, it can be used
to successfully connect to a VAX running VAX/VMS V5.5-2. On the other hand,
VAX/VMS V5.5-2 does not have the /APPLICATION qualifier to SET HOST so
outgoing RTERM connections are not possible from it.

Regards,
Peter Coghlan.